The ecosystems upon which humans depend are continually affected by a wide variety of forces, including domestic and wild herbivores, fire, drought, and climate change. For example, although it is becoming increasingly clear that loss of native animals can have far-reaching effects on ecosystems, experimental studies on the effects of loss or addition of different combinations of large mammals on ecosystems remain rare. While we are beginning to understand how ecosystems are (or are not) resilient in the face of individual forces such as grazing by herbivores, drought, and fire, this long-term experimental project will seek to understand the interactions amongst multiple forces that are likely to be complex and often unexpected. This research in a savanna rangeland will also document the interactions between livestock and native plants and animals that will inform the management of mixed-use landscapes in a world where most wildlife shares land with livestock production.
Extending our understanding of ecosystem resilience in the face of environmental variability requires long-term data examining multiple interacting drivers. The Kenya Long-term Exclosure Experiment (KLEE) uses semi-permeable barriers to create six different combinations of 1) cattle, 2) zebras and antelopes, and 3) elephants and giraffes, along with controlled burns, and across multiple drought cycles. Leveraging and extending more than 25 years of data, the Kenya Long-term Exclosure Experiment will ask: 1) how does the stability and resilience of this savanna ecosystem change under multiple experimental and natural stressors over multiple decades?, and 2) is there a discernable structure (e.g., hierarchy) of stressors to which the ecosystem responds? While some studies have examined aspects of these questions, the research team is in a unique position to address them across long and ecologically relevant periods of time, and with multiple experimental drivers. Although it has been suggested that multiple stressors synergistically lead to ecosystem thresholds from which recovery is not possible, the long-term data from this system has begun to suggest interactive mechanisms that buffer the ecosystem. Understanding interactive effects between multiple environmental stressors is integral to understanding ecosystem resilience.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
